Spheroidal Graphite Cast Iron

Ductile iron is primarily composed of iron, carbon, and silicon. When a spheroidizing agent is added to the molten iron, carbon primarily precipitates as spherical graphite, leading to the solidification of ductile iron. The conventional production process for ductile iron involves adding a small amount of magnesium to low-sulfur molten iron. Since magnesium promotes the formation of carbides, silicon must also be added to counteract this effect. This treatment results in graphite forming spherical shapes. Unlike gray cast iron, ductile iron does not form eutectic colonies during the solidification process. Typically, the size of the graphite spheres is about 1.0% of that of well-formed eutectic colonies in gray cast iron.